import numpy as np  # 一般以np为别名

a = np.array([2, 0, 1, 5])
print(a)
print(a[:3])
print(a.min())
a.sort()  # a被覆盖
print(a)
b = np.array([[1, 2, 3], [4, 5, 6]])
print(b*b)
